78 KZ650B stock carbs with kerker and pods

now that I have your attention, my setup is a 78 650B with stock carbs, non-accelerator pump model. The bike has a Kerker and pods. A 110 main really isnt that big for this setup is it?? I dont think so...

I only have about 30 miles on the bike since owning it and rebuilding it, and at high rpm it starts to break up. I thought it was over-jetted and too rich but was surprised to see a 110 main. So now I'm thinking that my advancer isnt working correctly. Anyone else think the same or am I missing something else??

Your main is probably too small with that set up. On my 77 kz650 with stock carbs, Emgo pods, MAC 4-1 (w/ baffle) I was running 17.5 pilot jets, needle on the 4th clip, and 115 mains. Minus the baffle I had to jump up to 117.5 mains.

just rechecked the advancer. It works like new.

Lean shouldnt break up and act like a rev limiter, I've always seen lean as a sag in power

the plugs are a little too dark to be lean.

my all stock 78' 650 is 15 on the pilot and 102 on the mains. it will pull cleanly to redline, the 110 seem like they may be a tad fat. you are certain the ignition is up to snuff? mine use to break up pretty bad above 6k or so, but i change the points out for kawasaki electronic and all is well now. the only thing i plan for the carbs is 17.5 pilots just to try and improve the tip-in a bit.

Did you read the plugs just off a wide open throttle plug chop or after mixed riding? If mixed riding you won't get an accurate plug read because you could be a little rich in the mid circuit which can mask the lean read on the main jet. I went rounds with that until I did a plug chop for every circuit to make sure they were all dialed in. My mid range was rich, most of my riding occurred on the needle circuit, so the few times I cracked WOT the plugs never got a pure reading of the main jet circuit...

yeah I will check. I also have an off-idle stumble in the low circuit. I brake into a corner, roll back on the throttle and get a little cutout but then it comes right back on. the pilots are 15

oh man its getting sweet now. I opened my low end airscrews and leaned out the low. the off-idle stumble is gone, and the upper cutout is getting a lot better. I'm going to go maybe another 1/4 turn lean on the low circuit airscrews.

So here's another related question. I use my choke as an indicator of mixture at various throttle settings. I set my throttle at the setting I want, then let the bike stabilize at the speed then start to open the choke.

If it stumbles worse, then its still too rich- if it smoothes out then its lean and asking for fuel. So I did a high speed run, just into the stumble zone and opened the choke. It stumbled worse, so I figure its still a bit rich up top.

Tell me whether I'm on track with this thinking....